Invasive squamous cell carcinoma of the skin is a significant problem in the U.S. with over one million cases annually. With a rising incidence and with surgery and radiation therapy as the only feasible treatment options, the need for development of more specific molecular agents to combat this disease is great. Towards this end, this proposal seeks to functionally characterize important components of the dermal-epidermal junction to determine how basement membrane proteins act as a significant driving force for invasion and progression of cutaneous squamous cell carcinoma. Laminin-332 is an essential component of the epidermal basement membrane, and is required for epidermal tumorigenesis as we have shown through use of an in vivo model of human cutaneous SCC. Recent data suggest that laminin-332's proteolytic modifications, its binding to collagen VII and its interaction with a6[unreadable]4 integrin each play important roles in SCC tumorigenesis, however a unified model of laminin-332 function in SCC which incorporates all of these features is lacking. In addition to a6[unreadable]4 integrin, several other cell surface receptors interact with laminin-332, including syndecan-1, c-Met and EGFR, and these receptors may also participate in laminin-332 derived signaling during SCC tumorigenesis. How these molecules coordinate together to activate pro-tumorigenic signaling pathways in SCC remains to be fully elucidated and is the focus of this proposal. First we plan to study the contributions of individual domains of laminin-332 to this process by both genetic deletion and antibody inhibition. We will also elucidate the pro-tumorigenic signaling contributed by specific residues contained in [unreadable]4 integrin. Second, we will examine the role of [unreadable]4 integrin associated molecules to understand how they, with laminin-332 and [unreadable]4 integrin, coordinate proliferation, cellular invasion, laminin-332 deposition, metalloproteinase activity and other functions essential for carcinoma progression. Finally, based on preliminary data showing specific inhibition of SCC tumorigenesis without disruption of normal skin cohesion, using an antibody against the G45 domain of laminin-332, we plan to develop and test a panel of antibodies against other laminin-332 domains as well as a collagen VII NC1 antibody. In these studies, we will functionally characterize how these antibodies act on SCC tumorigenesis, as well as normal skin. We will also determine whether combination antibody therapy can produce synergistic carcinoma inhibition. At the end of the proposed funding period, we hope to have answered fundamental questions about the role of the extracellular matrix in SCC tumorigenesis and to learn new information which has the potential for the development of novel and specific therapies for cutaneous SCC. PUBLIC HEALTH RELEVANCE: Squamous cell carcinoma (SCC) of the skin is the second most common human cancer, but effective and specific molecular therapies for this disease are lacking. This proposal focuses on understanding the critical role that the dermal-epidermal basement membrane proteins laminin-332 and a6[unreadable]4 integrin play in facilitating SCC progression and invasion. This proposal also seeks to develop novel and specific molecular therapies to inhibit the function of laminin-332 and associated molecules in SCC without disrupting normal skin tissue.